This invention relates to a fluid delivery apparatus and an associated method and more particularly to a fluid delivery apparatus in which a predetermined pressure waveform is introduced into a conduit, such as a human saphenous vein.
Fluid delivery apparatus which mock the circulation of blood in humans are extremely useful to test various medical devices, such as artificial heart valves. This apparatus is intended for exposing body tissues, such as a vascular tissue, to pulsatile flow. The rationale for this apparatus is the compelling evidence that the saphenous vein used in coronary bypass operations, once implanted in the arterial circulation, develops atherosclerosis (hardening of the arteries) at an accelerated rate. C. M. Grondin et al., "Coronary Artery Bypass Grafting With Saphenous Vein", Circulation, Supplement I, Vol. 79, No. 6, June 1989, pp. 1-24-1-29. One of the hypotheses is that because the saphenous vein is exposed to the pressure and flow present in the arterial (versus venous) circulation the subsequent "arterialization" of the saphenous vein may be an important component in the disease process. This hypothesis is, in part, supported by the excellent viability of internal mammary artery grafts (versus saphenous vein grafts) in which atherosclerotic degeneration is generally absent. M. E. Shelton et al., "A Comparison of Morphologic and Angiographic Findings in Long-Term Internal Mammary Artery and Saphenous Vein Bypass Grafts", J. Am. College of Cardiology, Vol. 11, No. 2, February 1988, pp. 297-307.
What is needed, therefore, is a fluid delivery apparatus in which pressure waveforms, which mimic the pressure waveforms of the human circulation system, are produced, so that the effects of "arterialization" can be studied. Furthermore, the fluid delivery apparatus can be used to "arterialize" vascular tissue so as to condition it for use in bypass surgery. These needs would be fulfilled by a precisely controlled fluid delivery apparatus that can effectively mimic the fluid pressure waveforms found in a human circulatory system.
In addition to the use of the fluid delivery apparatus for arterialization studies, many pharmaceutical manufacturers desire to test the effects of certain drugs on vascular tissue under conditions similar to those which are found in the human circulatory system. Presently, static tissue cultures are used for this purpose, or actual human trials are initiated. A fluid delivery apparatus would provide a more realistic test than the static culture tests yet safer then human trials. Also, using the fluid delivery apparatus would provide the researcher a way to isolate the effects of hemodynamic variables (such as pressure, flow and heart rate) on the vascular tissue. A fluid delivery apparatus in which predetermined and controlled pressure waveforms are produced is also needed for this application.
As can be seen, there is a need for a fluid delivery system that efficiently and precisely controls the pressure waveform that is introduced into a conduit, such as a human saphenous vein.